To answer your question Richard, yes the 327/350 Corvette engine used deep groove pulleys, so I'm not sure why your belt is too long. I've attached the 1967 and 1968 belt charts from the Corvette P&A and it shows the 3837810 belt being used for that engine. And like Kerry said, that same belt is listed in the 67 Camaro AIM for the L78.
The overall length of that belt is supposed to be 3/8" x 34-3/8" so you might want to measure yours. Maybe you just got a bad one?